The terrific "DIG!" offers a unique chance to watch two classic rock band scenarios unfold simultaneously. Ondi Timoner's docu charts the Dandy Warhols and Brian Jonestown Massacre from mutual warm-'n'-fuzziness through an ugly "feud" created by the former's success and BJM leader Anton Newcombe's self-destructive behavior.

The terrific “DIG!” offers a unique chance to watch two classic rock band scenarios unfold simultaneously. Shot over seven years, Ondi Timoner’s docu charts Portland’s Dandy Warhols and San Francisco’s Brian Jonestown Massacre from mutual warm-‘n’-fuzziness through an ugly “feud” created by the former’s success and BJM leader Anton Newcombe’s self-destructive behavior. Beyond the lure of going intimately behind the scenes with two excellent indie outfits (one drastically underappreciated), “DIG!” offers fascinating insights into how some vivid personalities fare in the music industry. With special marketing emphasis toward alt-rock fans, pic could prove a sleeper in specialized release.

Involved in making vidclips and other music-related promo materials since the mid-’90s, feature debutante Timoner met these two bands at about the same time. The level of long-haul access on display here is quite remarkable — her skeleton crew seems to have missed nary a dramatic moment in either unit’s history to date. (In the BJM’s case, encompassing every bit of drama would probably necessitate a running time longer than the “Rings” trilogy several times over.)

Formed in 1990 in S.F.’s fabled Haight-Ashbury district, the Brian Jonestown Massacre (named after both the late Rolling Stones icon and the ’70s Guyana cult mass suicide) duly revisited psychedelic sounds of yore, elevated beyond mere imitation by indie rock influence as well as leader Anton Newcombe’s formidable songwriting and multi-instrumental skills.

Aiming to “kick off a revolution” in musical terms, they found like-minded allies a few years later in the Dandy Warhols, which had its own charismatic leader in Courtney Taylor-Taylor and a similar semi-retro, punchy yet hypnotic sound.

For some time the two outfits played gigs together, crashed at each other’s digs, planned to build a studio together, et al. But differences soon emerged, then widened into chasms. One Dandy admits, “We’re the most well-adjusted band in America” — they get along well (though one member does depart after an argument over royalties), none are from broken homes; by pic’s end, half are happily married.

By contrast, the Massacre is as dysfunctional as they come, with Newcombe bountifully living out Taylor’s description of him as both “by far the craziest and most talented musician I ever met.” He’s capable of writing and producing albums (up to three in one year) on a shoestring. Yet he’s also an unpredictable, irrational danger zone whose messianic vision of himself is flipsided by fact that (as one soon-to-be-ex-girlfriend notes) “heroin makes him evil.” We see Newcombe throw on-stage tantrums, provoke the audience, pick fights and attack his own bandmates. At last count he’s gone through over 40 BJM members.

One of pic’s most crushing moments is interview with his alcoholic and schizophrenic father, followed by news that the latter committed suicide on Anton’s next birthday. Considered a genius by many, Newcombe finds ways to blow every possibility for advancement. Timoner’s camera records in grisly detail a crucial industry showcase at L.A.’s Viper Room, which he turns into a full-on circus of childish, unprofessional behavior — effectively blackballing group from the major-label world.

Meanwhile the Dandys are signed by Capitol Records. Their public and material success stirs Newcombe’s furious resentment. Soon he’s recording songs ridiculing the Dandys and sending them not-so-veiled threats. To their credit, the Dandys still insist Anton is an extraordinary talent — “my greatest inspiration, my greatest regret,” Courtney sighs.